Physical modelling of shallow skirted foundations under transient and sustained uplift

The response during transient uplift has been compared with theoretical undrained bearing capacity factors and failure mechanisms have been interpreted from visual observations during and after testing. The foundation response under sustained uplift has been summarised as ‘backbone curves’ showing the degradation of uplift capacity with time. No theoretical or analytical solutions of the degradation of uplift capacity under sustained load exist for comparison with the experimental observations. Local shear was found to govern failure of the shorter skirted foundation, d/D = 0.15, while reverse end bearing was mobilised with the longer skirt, d/D = 0.3. As reverse end bearing was not mobilised with the smaller embedment ratio, the remainder of the experimental programme concentrated on the longer skirted foundation model. Examination of transient capacity under tension and compression load paths was considered next (Chapter 3) to establish the magnitude and robustness of the uplift response in comparison with the compression resistance...